The present invention relates to an electrophotographic photosensitive member, particularly one having a surface layer comprising a specific resin, a process cartridge and an electrophotographic apparatus including the electrophotographic photosensitive member, and a process for producing the electrophotographic photosensitive member.
In recent years, as photoconductor materials for use in electrophotographic photosensitive members, organic photoconductor materials are noted for their advantages, such as high productivity and non-pollution characteristic and have been widely used.
In many cases, there have been used function separation-type electrophotographic photosensitive members having a structure including a charge generation layer and a charge transport layer in lamination so as to satisfy both electrical and mechanical characteristics. On the other hand, an electrophotographic photosensitive member is required to satisfy sensitivity, electrical characteristic, optical characteristic and durability corresponding to an electrophotographic process where it is used, as a matter of course.
Particularly, the surface of a photosensitive member is directly subjected to various electrical and mechanical external forces during various steps of charging, exposure, development with a toner, transfer onto paper and cleaning, so that durability against these forces is required. More specifically, the photosensitive member is required to exhibit durability against lowering in photosensitivity, lowering in chargeability, increase in residual potential, abrasion and occurrence of scars at the surface due to abrasion and also transferability of a toner image and a cleaning performance of a residual toner after the transfer. For that purpose, the photosensitive member is required to have a smaller surface energy and a higher lubricity and it is desirable that these performances are not lowered even on repetitive use.
It has been difficult for the electrophotographic photosensitive member using an organic photoconductor to satisfy the above properties, particularly the durability.
The surface layer of the electrophotographic photosensitive member using an organic photoconductor is generally a thin resin layer, and the property of the resin is very important. As resins satisfying the above-mentioned requirements to some extent, acrylic resin, polycarbonate resin, etc., have been used commercially in recent years. However, this does not mean that all the above-mentioned properties are satisfied by these resins. Particularly, it is difficult to say that these resins have a sufficiently high film hardness in order to realize a higher durability. More specifically, a surface layer of these resins has been liable to cause abrasion or scars during repetitive use.
Further, in compliance with a demand for a higher sensitivity in recent years, relatively large amounts of low-molecular weight compounds, such as a charge-transporting material, are added in many cases. In such cases, a problem is liable to be encountered that such low-molecular weight compounds are precipitated or exuded during a storage of the electrophotographic photosensitive member. Further, when a mechanical oil or a resinous component is attached to the surface of the photosensitive member, a cracking is caused to occur in some cases.
For solving these problems, the use of a cured resin for constituting a charge transport layer has been proposed, e.g., in Japanese Laid-Open Patent Application (JP-A) 2-127652. According to this proposal, the resultant charge transport layer comprising a cured and crosslinked resin has provided remarkably increased surface strength to improve resistances to abrasion, scars, precipitation and cracking during repetitive use.
However, in a charge transport layer composed of an organic charge-transporting material and a cured binder resin, the charge-transporting performance is largely affected by the resin, and in case of using a cured resin layer having a sufficiently high hardness, the charge-transporting performance is liable to be lowered to result in an increased residual potential on repetitive use, so that it has not fully succeeded in satisfying both the hardness and charge-transporting performances at higher levels.
A generic object of the present invention is to provide an electrophotographic photosensitive member having solved the above mentioned problems.
A more specific object of the present invention is to provide an electrophotographic photosensitive member having a surface layer exhibiting a high film strength leading to improved anti-abrasion and anti-scar characteristics, and also good anti-precipitation and anti-cracking characteristics.
Another object of the present invention is to provide an electrophotographic photosensitive member exhibiting very little change or deterioration of photosensitive member performances, such as increase in residual potential in repetitive use, thus being capable of exhibiting stable performances in repetitive use.
A further object of the present invention is to provide a process cartridge and an electrophotographic apparatus including such an electrophotographic photosensitive member, capable of retaining high-quality image-forming performances for a long period.
A still further object of the present invention is to provide a process for producing such an electrophotographic photosensitive member.
According to the present invention, there is provided an electrophotographic photosensitive member, comprising:
a support and a photosensitive layer disposed on the support, wherein
the photosensitive layer comprises a charge transporting material and a resin obtained by radiation curing of a compound having a functional group represented by the following formula (1): 
xe2x80x83wherein Ar denotes a substituted or unsubstituted arylene group and R1 denotes a hydrogen atom or methyl group.
According to the present invention, there is also provided a process cartridge, comprising: the above-mentioned electrophotographic photosensitive member and at least one means selected from the group consisting of charging means, developing means and cleaning means; said electrophotographic photosensitive member and said at least one means being integrally supported and detachably mountable to a main assembly of an electrophotographic apparatus.
The present invention further provides an electrophotographic apparatus, comprising: the above-mentioned electrophotographic photosensitive member, and charging means, developing means and transfer means respectively disposed opposite to the electrophotographic photosensitive member.
According to another aspect of the present invention, there is provided a process for producing an electrophotographic photosensitive member, comprising a photosensitive layer-forming step of forming a photosensitive layer containing a charge-transporting material as a surface layer on an electroconductive support; the photosensitive layer-forming step including a step of radiation-curing a compound having the above-mentioned functional group of the formula (1).
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawing.